The donkey evolved from the "mule show" that appeared in the Tertiary period 60 million to 70 million years ago. Donkeys belong to the subgenera Mammalia, Perissodactlya, Equidae, Equus and Asinus in zoological classification. Regarding the origin and evolution of donkeys, before the Pleistocene, there was no conclusive paleontological evidence that could distinguish horses, donkeys and zebras, and the structural features of fossils could not distinguish them into different species, in fact, horses, donkeys and zebras are three different subgenera contained in the genus Equus. However, since the Sanmen horse, especially in the flood period, fossil wild ass have appeared in many parts of China, and are associated with fossil wild horses. These wild ass fossils are called by some scholars as Equus hemio - nus pallus. So far, there are different understandings of whether the wild asses living in the grasslands of northwest China and the Qinghai-Tibet Plateau are the remains of fossilized wild asses, and their evolutionary relationship with modern domestic donkeys.
Wild donkey species and their distribution.
The wild ass in the world is divided into Asian wild asses (e.).hemionus ), African wild ass (ea fricanus) and a wild ass (eKiang) 3 species.
Asian wild ass. It is mainly distributed in the interior of Asia such as Arabia, Syria, India and the desert areas and arid grasslands in the west of China. The Asian wild ass is also known as the Asian wild ass in China, and there are also sources that the Asian wild ass is a subspecies of the Asian wild ass. The Asian wild ass has short limbs and a short, broad head (length 41 53.).5 cm), the ears are long and pointed (18 long5 27 cm), the nape of the neck has a short mane (about 10 cm long), the tail is thicker and the apex is covered with long hairs (tail length 40 56 cm, hair length 25 60 cm). smaller in size than a horse, but larger than a domestic donkey; The body length is 198 244 cm, the weight is 200 260 kg, and the shoulder height is 110 140 cm. The limbs are stubby and short, the tendons are well developed, the hooves are smaller than those of a horse and larger than that of a domestic donkey, and the quality is firm and smooth. There are four extant wild subspecies of the Asian wild ass: Mongolian wild ass (e.).Hemionus hemionus), also known as the Gobi wild ass, Mongolian wild ass is more concentrated in central Asia, China and Mongolia adjacent to the vast area, Central Asia in the south-central part of Turkmenistan and Iran, Afghanistan border a small area. Turkmenkuran donkey (eHemionus Kulan ), which is found on the territory of Turkmenistan. Indian wild ass (e.).Hemionus Khur is found in the saline deserts, grasslands and jungles of Gujarat, India. At present, the wild population has reached about 4,000 individuals, second only to the Mongolian wild ass. Onagle donkey (e.).Hemionus onager), also known as Iranian donkey, is found in India, Iran, Turkmenistan, Afghanistan and Tajikistan, and is connected to the southern distribution of Turkmenkuran donkeys. The Syrian wild ass (e h .Hemippus was extinct in 1927. Some literature in the past referred to the Turkmenkuran ass as the Mongolian wild ass, and now the two are considered to be different wild subspecies.
The distribution area of the Asian wild ass extends from the Hami Basin in the west to the Daxing'an Mountains in the east, including the southeastern part of Inner Mongolia, the western part of Gansu Province, the northeast part of Inner Mongolia, Qinghai Province and the vast area. In the 20th century, the distribution of the Asian wild ass could reach at least the westernmost edge of the Junggar Basin along Ganjia Lake, which was associated with the Przewalski's horse (e.).Ferus prezwalskii) is apparently homogeneous. In the past half century, with the increase of human economic activities, the distribution range of Asian wild ass has been greatly reduced, and it has been compressed to the narrow area of the central west of the original distribution area, and the donkeys that live here are called Mongolian wild asses (now Xinjiang Altun Mountain Nature Reserve has its population), and another part enters the plateau subarctic open meadow and frozen semi-desert and desert area at an altitude of 3800 5000m, and the wild ass that lives here is called ** wild ass (Xinjiang Altun Mountain Nature Reserve has its population), Now an independent species, the Riga Zoo in Russia is engaged in the restoration of wild asses.
Part of the Asian wild ass inhabits the desert area with open terrain and sparse vegetation, the average annual temperature is about 5, the lowest temperature in January is below 30, the highest temperature in July is above 50, the winter is cold and less snow, the summer is dry and hot, the annual precipitation is more than 200mm, and the annual evaporation is up to more than 2000mm. The other part of the wild ass inhabits the highland subarctic meadows at an altitude of 3800 to 5000 m. The average annual temperature is 1September, January the lowest temperature is 412. The highest temperature in July is 226℃。Winter and spring are cold, rain and snow are scarce, dry and windy; Summer and autumn are cool and humid, with a large temperature difference between day and night, and the annual precipitation is 400mm, which is unevenly distributed throughout the year. The soils are mainly distributed in hidden peat bogs, zonal alpine and subalpine meadows.
Wild asses are migratory, have no fixed habitat, and live a migratory life. In summer, they like to spend time in areas with abundant water and grass, and in winter they move to hilly valleys that are sheltered from the wind and the sun, and sometimes they migrate horizontally over long distances to follow the excellent environment. They are gregarious, often in small groups, and in winter they form larger groups. Because they inhabit an open environment, they have a keen sense of sight, hearing and smell, and can often detect foreign objects within 500m, and gallop at full speed within 300m, and their galloping power is strong. When escaping, the male donkey is in front, the young donkey is in the middle, and the female donkey is behind. Wild by nature, not easy to approach, timid and frightened, not afraid of wind and frost, sun exposure, and resistant to severe cold. The breeding season is from August to September every year, and the mating season is fierce. The male donkey has a neighing voice similar to that of a horse during courtship, but it is shorter and hoarse. The gestation period of the female donkey with the donkey is 360 days, 1 litter and 1 foal, and the young donkey reaches sexual maturity at the age of 4.
Wild donkey food is mainly grasses, sedges and lilis, and the common food is needle grass, moss, vanilla, early maturing grass, rhizome, wild onion, rhodiola and artemisia grass, etc., strong hunger resistance, can not eat for several days, after full food, during the day is not far from the water source activities or rest. In the evening, return to the higher and secluded hills and spend the night, go to a place with a water source in the early morning to drink water, and often bathe in the wide valley rivers or swamps in the summer.
Wild ass moults from May to July every year, the distribution of coat color is different, the nose end is milky white, the forehead is yellow, the back of the ears is light brown, the inside of the ears is white, the dorsal side of the neck, shoulders, back, and waist are yellowish tan, there is a dark brown back stripe from the back ** to the tail, the abdomen of the neck, chest, body side, and abdomen are white with sand, and there is a clear dividing line with the dorsal lines of the back lines, the line is slightly close to the lower part of the ventral side, the color of the mane is darker, the dorsal side of the buttocks is sandy brown, and the ventral side is nearly white. The tail hairs are dark brown on the dorsal side and sandy on the ventral side. The front and rear crowns have a dark ring. The winter coat is darker, grayish-brown and lighter on the ventral side, but the dividing line with the dorsal coat color is weakened and not very obvious.
Also known as the donkey, it is now thought to be the ancestor of the modern domestic donkey and is found in deserts and other arid regions of northeastern Africa such as Ethiopia, Eritrea and Somalia. Wild species in Sudan, Egypt and Libya have become extinct. Its coat color is cyan and iron blue, the eagle wings, dorsal line and limbs are distinctly zebra, the ears are long, and the tail hair is more. African wild ass includes domestic donkeys (e.).1 domesticated subspecies of Asinus and Nubian donkey (EAfricanus) (Figure 1-1), Somali donkey (Esomaliensis (Figs. 1-2) 2 wild subspecies. The Nubian wild ass is the direct ancestor of the domestic donkey, which began to be domesticated into the domestic donkey in the late Neolithic period 6,000 years ago, and is now endangered in the Nubian desert region of the upper Nile River in Africa and the southern Ethiopian plateau. Somali donkeys, found in the southeastern part of the Nubian Desert and the southeastern Ethiopian highlands and western Somalia, are also on the verge of extinction.
*Donkey. Also known as Kang donkey (e.).Hemionus kiang), once thought to be a subspecies of the Asian wild ass, has now become an independent species. **Wild ass is found on the Tibetan Plateau and its adjoining regions, and is only found abroad in Nepal, Kashmir and Sikkim in India.
Wild ass in China includes Mongolian wild ass and ** wild ass, the former is distributed in the Mongolian new area, and the latter is distributed in the Qinghai-Tibet area.
Mongolian wild ass Mongolian wild ass is distributed in 14 counties (banners) of 3 provinces and autonomous regions of Inner Mongolia, Gansu and Xinjiang in China. The distribution area is a typical temperate continental climate, and the temperature tends to be hot and cold. Precipitation is low, evaporation far exceeds precipitation, the climate is extremely dry, and the wind and sand are seriously harmed. The vegetation structure is simple. Due to the extremely harsh natural environmental conditions, the population reproduces slowly despite its wide habitat area and range of activities. The Mongolian wild ass resembles a mule, with a body length of up to 260cm, a shoulder height of about 120cm, a tail length of about 80cm, and a weight of about 250kg. The snout is slightly elongated, and the ears are long and pointed. The tail is elongated, the tip hairs are long, brownish-yellow. The limbs are strong and powerful, and the hooves are smaller than those of a horse but slightly larger than that of a domestic donkey. The back of the neck has a short mane, the dorsal side, shoulders, and back of the neck are light yellow-brown, and there is a brown dorsal line extending to the base of the tail, and the lower neck, chest, body, and abdomen are yellowish-white, and there is no obvious dividing line with the dorsal coat color.
Due to the harsh natural environmental conditions, scarcity of food resources and the impact of indiscriminate hunting, the population reproduction is slow despite the wide habitat area and range of activities. The population remains small, with 6,000,6500 Mongolian wild asses worldwide and an estimated total population of no more than 2,000 in our country. The species has been listed as an endangered species in the world, and the import and export of Mongolian wild ass is strictly prohibited or controlled internationally, and the Mongolian wild ass is a rare and endangered animal in China.
* Wild ass in China's distribution area involves 30 counties (cities) in Qinghai, Xinjiang, Gansu and Sichuan, these areas are cold, the average annual temperature is less than 0, and many places have frost all year round or almost all year round. The air in the plateau is thin and dry, and the solar radiation is strong. There are many rivers and lakes in the territory. The vegetation is dominated by alpine meadow steppe and alpine desert steppe. **The appearance of the wild ass is similar to that of the Mongolian wild ass, which is larger than the Mongolian wild ass and has a shoulder height of 15m。The head is shorter, the ears are longer, and it is able to rotate flexibly;The snout is round and blunt, and the color is dark. The coat of the whole body is mainly reddish-brown, the tip of the ears, the dorsal line, the mane, and the end of the tail are dark, and the coat above the snout, under the neck, chest, abdomen, limbs, etc. is stained with white, and the color boundary on both sides of the trunk is clear. **The number of wild asses on the Tibetan Plateau is nearly 90,000.